There have been practical applications of solar power generation apparatus for converting solar energy into electrical power, but to lower costs and obtain more power, there have been practical applications of concentrating solar power generation apparatus, a type with which sunlight concentrated by a concentrating lens irradiates a solar cell element with a smaller surface area than the light receiving area of the concentrating lens, and electrical power is taken off.
With a concentrating solar power generation apparatus, sunlight is concentrated with a concentrating lens, so the solar cell element may have a smaller light receiving surface area that can receive sunlight that has been concentrated with an optical system. In other words, since a solar cell element may be used that is smaller in size than the light receiving surface area of the concentrating lens, the solar cell element can be made more compact, which means that the amount of solar cell elements, which are the most costly element in a solar power generation apparatus, can be reduced, and costs can be lowered. Because of these advantages, concentrating solar power generation apparatus are being utilized for power supply in locales where power can be generated using a large surface area, for example.
A concentrating solar power generation apparatus has been proposed which has a simple structure in which a solar cell module is attached to a support frame, with adequate strength and stiffness being obtained without having to increase weight, so good heat dissipation can be achieved—(see, for example, Patent Document 1).
Meanwhile, FIG. 17 is a diagram illustrating a conventional example of a concentrating solar power generation apparatus. FIG. 17(A) is a plan view giving a general overview as seen from the plane of sunlight incidence, and FIG. 17(B) is a cross-sectional view of the cross section along the B-B line in FIG. 17(A).
A concentrating solar power generation apparatus 100 in this conventional example (see, for example, Patent Document 2) comprises a case 101 that is open at one end face, non-imaging Fresnel lenses 102 fitted into the opening in the case 101 so as to function as a primary optical system, a seat plate 103 provided to the bottom of the case 101, solar cell elements 104 disposed on the bottom face of the case 101, that is, over the seat plate 103, which is the concentrating position of the non-imaging Fresnel lenses 102, and tubular reflecting mirrors 105 that function as a secondary optical system.
Patent Document 1: JP H11-284217A
Patent Document 2: JP 2003-174183A
However, the concentrating lens of a concentrating solar power generation apparatus has to be disposed in a precise positional relationship to the solar cell element, so good alignment is necessary. Furthermore, concentration at the light receiving position entails a tremendous amount of energy, so some means for heat dissipation such as preventing damage by irradiation to the area around the solar cell element is needed.
Also, a concentrating solar power generation apparatus is often installed in deserts and other locales subject to extreme changes in temperature, so some means for dealing with thermal expansion caused by rising temperature is also necessary.
Specifically, to obtain a solar power generation apparatus with which electrical power can be reliably obtained from sunlight, it is extremely important to employ a suitable means for dealing with heat and light concentration in the mounting of the solar cell element, the adjustment of the positional relationship between the solar cell element and the optical system, and so forth.
The technology described herein was conceived in light of this situation, and it is an object thereof to provide a concentrating solar power generation unit and a concentrating solar power generation apparatus that comprise a mounting plate on which a solar cell element is mounted, a light shield that covers the mounting plate and has a transmission hole for transmitting sunlight, a concentrating lens for concentrating sunlight on the light receiving region of the solar cell element, and a frame for aligning the solar cell element and the concentrating lens, the result of which is that assembly is easier, productivity is higher, maintenance (repair and inspection) work is easier, optical members can be easily aligned, and the effect is excellent with respect to heat and sunlight.
Meanwhile, problems with the above-mentioned concentrating solar power generation apparatus 100 shown in FIG. 17 are that the tubular reflecting mirrors 105 corresponding to the solar cell elements 104 are needed to concentrate the sunlight Ls, and that frames corresponding to each of the non-imaging Fresnel lenses 102 have to be formed in the case 101 to support the non-imaging Fresnel lenses 102, and so forth, all of which makes the optical system more complicated and the manufacturing process more complicated.
Also, since the non-imaging Fresnel lenses 102 are supported by the frames of the case 101, there is a limit to how big the case can be, and a problem is that it is difficult to obtain a concentrating solar power generation apparatus 100 capable of concentrating light over a large surface area.
Also, since the non-imaging Fresnel lenses 102 are supported by the frames of the case 101, alignment is difficult (for example, the precision of the frame shape has to be increased, and every frame has to be aligned with the concentrating positions), and the manufacturing process is more complicated, and also, precise alignment is difficult.
Also, when a reflection tube or other such secondary optical system is used, the sunlight that reaches the solar cell elements 104 always passes through the reflection tube, etc., so a problem is that optical loss is caused by reflection or poor transmissivity of the reflection tube itself.
The technology described herein was conceived in light of this situation, and it is an object thereof to provide a concentrating lens, a concentrating lens structure, and a method for manufacturing the same, with which concentration is even over the entire concentrating region (the light receiving region of the solar cell element), reliable concentration is possible, and concentration efficiency can be improved, by using a concentrating lens comprising a flat first face and a second face on which is formed a flat region parallel to the first face and a protruding region having inclined faces that are inclined with respect to the first face, or by using a concentrating lens structure in which this concentrating lens is supported by a translucent substrate.
It is another object of the technology described herein to provide a concentrating lens structure with which the flat region of a concentrating lens is utilized to align the concentrating lens and a concentrating region, which allows precise alignment to be easily accomplished with a simple optical system, so the manufacturing process can be simplified and concentration efficiency can be increased, and to provide a method for manufacturing this concentrating lens structure.
It is another object of the technology described herein to provide a concentrating solar power generation apparatus that makes use of the above-mentioned concentrating lens structure, which allows precise alignment to be easily accomplished between the concentrating lens and the light receiving region (concentrating region) of the solar cell element, so the manufacturing process can be simplified, concentration efficiency can be increased, and also good power generation efficiency can be achieved.
The concentrating solar power generation unit according to the technology described herein is a concentrating solar power generation unit that generates electricity by irradiating a solar cell element with sunlight that has been concentrated with a concentrating lens, comprising a mounting plate on which the solar cell element is mounted, a light shield that has a transmission hole for irradiating a light receiving region of the solar cell element with sunlight and covers the mounting plate, a concentrating lens disposed across from the light shield, for concentrating sunlight on the light receiving region, and a frame for aligning and supporting the solar cell element and the concentrating lens.
Preferably, the light shield is formed integrally with the frame.
Preferably, the light shield has a bent portion in which the peripheral edge of the transmission hole is bent to the mounting plate side.
Preferably, the approximate middle of an end side of the mounting plate is fixed to the light shield, and the approximate middle of an end side of the concentrating lens is fixed to the upper end of the frame.
Preferably, a plurality of the solar cell elements are disposed on the mounting plate.
Preferably, the concentrating lens is disposed and supported on a translucent substrate corresponding to each of the plurality of solar cell elements.
Preferably, the approximate middle of an end side of the mounting plate in the lengthwise direction is fixed to the light shield.
Preferably, the approximate middle of an end side of the translucent substrate in the lengthwise direction is fixed to the upper end of the frame.
Preferably, the mounting plate and the translucent substrate are divided into a plurality of parts in the lengthwise direction of the frame.
The concentrating solar power generation apparatus according to the technology described herein is a concentrating solar power generation apparatus comprising a concentrating solar power generation unit, wherein the concentrating solar power generation unit is the concentrating solar power generation unit according to the technology described herein, and is constituted to allow tracking drive.
The concentrating lens according to the technology described herein is a concentrating lens having a flat first face and a second face on which are formed protrusions having an inclined face that is inclined with respect to the first face, wherein the second face comprises a flat region having a plane parallel to the first face, and a protruding region having the protrusions.
Preferably, the boundary between the flat region and the protruding region is demarcated by a step between the flat region and the protrusions.
Preferably, the flat region is demarcated by a circle having a diameter sufficient to surround the light receiving region of a solar cell element to be disposed across therefrom, and the protrusions are formed concentrically with respect to the flat region.
Preferably, the inclination angle of the inclined face with respect to the first face, and the inclination change pitch, which is the pitch at which this inclination angle is changed, are set so that light of a wavelength band that determines the short-circuit current of the solar cell element is concentrated on the light receiving region.
The concentrating lens structure according to the technology described herein is a concentrating lens structure comprising a concentrating lens having a flat first face and a second face on which are formed protrusions having an inclined face that is inclined with respect to the first face and a translucent substrate that fixes and supports this concentrating lens, wherein the second face comprises a flat region having a plane parallel to the first face, and a protruding region having the protrusions, and the concentrating lens and the translucent substrate are aligned by using a boundary demarcated by a step between the flat region and the protrusions.
Preferably, a flat region fixing portion that fixes the concentrating lens and the translucent substrate so as to correspond to the flat region, and a peripheral edge fixing portion that fixes the concentrating lens and the translucent substrate so as to correspond to the peripheral edge of the protruding region, are formed between the translucent substrate and the first face.
Preferably, the flat region fixing portion and the peripheral edge fixing portion are formed by double-sided adhesive tape.
Preferably, a filled portion that is filled with an adhesive agent is formed between the translucent substrate and the first face.
Preferably, a plurality of the concentrating lenses are lined up on the translucent substrate.
The concentrating solar power generation unit according to the technology described herein is a concentrating solar power generation unit comprising a concentrating lens structure equipped with a concentrating lens and a translucent substrate that fixes and supports the concentrating lens, and a solar cell element disposed corresponding to the concentrating lens.
The concentrating lens structure manufacturing method according to the technology described herein is a method for manufacturing a concentrating lens structure that comprises a concentrating lens having on a second face a flat region having a plane parallel to a planar first face, and a protruding region in which are formed protrusions having an inclined face that is inclined with respect to the first face, and a translucent substrate that fixes and supports this concentrating lens, with the concentrating lens and the translucent substrate being aligned so that the flat region and a concentrating region faces each other, said method comprising the steps of aligning the flat region with a flat positioning piece of a positioning jig base provided with this flat positioning piece for determining the position of the flat region and with a substrate end positioning piece for determining the position of the end of the translucent substrate, forming a flat region fixing portion for fixing the concentrating lens and the translucent substrate at positions corresponding to the flat region on the first face, forming a peripheral edge fixing portion for fixing the concentrating lens and the translucent substrate at positions corresponding to the peripheral edge of the protruding region on the first face, butting the end of the translucent substrate against the substrate end positioning piece and joining the translucent substrate to the flat region fixing portion and the peripheral edge fixing portion, and filling the space between the translucent substrate and the concentrating lens with an adhesive agent.
The concentrating solar power generation unit and concentrating solar power generation apparatus according to the technology described herein include a light shield that covers a solar cell element and a mounting plate on which the solar cell element is mounted, and a frame that demarcates the positional relationship of the solar cell element and the concentrating lens, and the mounting plate and frame are configured separately, so productivity is improved due to the mounting of the solar cell element to the mounting plate, etc., maintenance and inspection are easier, workability and reliability are improved.
Also, since the alignment of the mounting plate and the translucent substrate (concentrating lens) with respect to the transmission hole can be accomplished using the structural members (frame and light shield) as a reference shape, it is easier to ensure precise alignment of the optical members (concentrating lens and translucent substrate) and the solar cell element. Also, because alignment precision can be enhanced, the irradiating sunlight can be utilized more efficiently.
Another effect of the concentrating solar power generation unit and concentrating solar power generation apparatus according to the technology described herein is that since the light shield prevents sunlight from irradiating the mounting plate on which the solar cell element is mounted, the mounting plate on which the solar cell element is mounted can be prevented from being damage.
With the concentrating lens according to the technology described herein, since the flat region is disposed across from the light receiving region, sunlight that is incident perpendicular to the flat region is also incident perpendicular to the light receiving region, and the sunlight incident on the protruding region is bent by the inclined faces and concentrated in the light receiving region. Therefore, the light incident on the flat region has no chromatic aberration caused by the concentrating lens, there is less variance in the optical intensity distribution at the light receiving face of the solar cell element, and power generation efficiency can be increased.
With the concentrating lens structure and its method of manufacture according to the technology described herein, since the concentrating lens and the translucent substrate (concentrating region) are aligned by using the boundary between the flat region and the protruding region, it is easy to accomplish precise alignment, and the manufacturing process can be simplified. Also, the mechanical strength of the concentrating lens can be increased by the translucent substrate, so the concentrating lens can have the shape required for concentrating light, and it is possible to provide a concentrating lens structure that has the desired concentration characteristics and is capable of concentration over a large surface area.
With the concentrating solar power generation unit according to the technology described herein, because the concentrating lens structure according to the technology described herein is used, the manufacturing process is simple and it is possible to provide a concentrating solar power generation apparatus with good concentration characteristics and high power generation efficiency and reliability.